CHARLESTON, W.Va. -- "Flowback" is the liquid that returns to the surface when a shale well is fractured. Figures for the amount of water required to fracture a shale well usually range from 3 million gallons to 5 million. Likewise, figures for the amount returning to the surface vary, but 20 percent seems reasonable.

As a ballpark figure, let's say a typical Marcellus well requires 4 million gallons to fracture. That is a cube of water 81 feet per side, or 800 truckloads at 5,000 gallons each.

If the flowback is 20 percent, that's 800,000 gallons, a cube 47 feet per side, the volume of five very comfortable houses.

Disposal is a major problem, both physical and financial. The traditional way to handle disposal, dating back to pioneer days is to throw it in the creek. But that is bad for people downstream. It was cow manure, brush and sewage when population density was small, but we have largely ended the nasty habit of disposing of things that way today.

Flowback is far worse than what had to be disposed of in the past. It has the fracturing chemicals and a huge load of material dissolved while below.  The temperature of the deep-down Marcellus Shale is a little below the boiling point of water at the surface, and the fracturing fluid is under great pressure. This makes it capable of dissolving a variety of compounds from the shale, including several uncommon in surface waters. 

Sometimes it's referred to as "residual waste," more frequently "brine." Most people know brine as a table salt solution. The ocean is brine. However, most inorganic compounds that are soluble are salts. It is a mistake to think any naturally formed brine has only the properties of a sodium chloride solution.  It may be far more corrosive, poisonous or concentrated.

Present in this Marcellus brine are barium and strontium, bromine, sometimes arsenic or manganese, along with the substances sent down by the driller. It is several times more concentrated than seawater.

So what to do with this brine is a major concern. The ingrained instinct is to dump it and forget it -- put it in a creek or anywhere out of sight. I have seen it sprayed on a dirt road in the summer for dust control. I noticed the spray did not stop when the truck got to hard road, though, but went on and on. Others have seen it used to melt ice on a road in winter. So where does the material go when it rains? In the creek. 

In some times and places, a legal way to get rid of it was "land disposal." What happens to the vegetation? And where does it go when it rains?

Another perfectly legal way to dispose of flowback at some times and places is to take it to a municipal water treatment plant. These plants use microorganisms and oxidation by air to remove sewage, food and other organic waste. The municipal water plant can do little or nothing for inorganic components fed to it. It is simply diluted and passed downstream, like in the old days, to the water intake of the next town. The bromine reacts with other things on the way to make carcinogenic compounds.

Another way to get rid of "frack water" is to reuse a portion of it for fracking. Sometimes some of it goes through a processing plant to remove impurities -- but what happens to the impurities?

Still another is to dump it in mine voids, where coal has been removed. Then it moves through the mine and through cracks and back out to the surface if the abandoned coal seam is above the valley floor. And then into streams.

Sometimes residual waste is pumped underground.  This requires relatively porous rock, unavailable in West Virginia and Pennsylvania. There are several wells in Ohio, and truck traffic is brisk to them. When you start pumping the volume equivalent of many houses down 10,000 feet every day, considerable pressure is needed. At least one Ohio well has disposed of so much brine that earthquakes have occurred.

Still another disposal method is to evaporate the water and volatile organic compounds from "frack ponds" on site. This is a source of considerable air pollution. Ponds are lined with impervious plastic to prevent leaks into the soil, more an ideal than an actuality. The final step may be removal to burial in a landfill or simply pushing it together on site and covering it with soil.  Both of these slow down the movement of the salts, but eventually, over geological time, much of it washes into the creek.

There is no public accounting for flowback disposal, and little concern for how it is done.   Does it "get lost" between the source at the well being fractured and some destination?

I get reports from the EPA almost daily, sometimes two or three a day, of cleanups of chemical contamination, brownfields. I am a member of an environmental group which is remediating acid mine drainage from mines dug over 100 years ago. I see the Marcellus industry repeating the same externalization of cost practiced by these earlier industries. Somebody else will pay for the industry's legitimate business cost of gas extraction. 

The scale is vast. Figures above are for one well. Full exploitation of the Marcellus will involve hundreds of thousands of wells.

Dr. Bond, of Jane Lew, Lewis County, is retired as a Salem College organic chemistry professor.